silicon vs germanium

[Splodrod]

Hi
When doing guitar effects mods some of them change a silicon trany for a
germanium one. Why, what effect might this have on the sound?
Cheers BB

 

[Lostgallifreyan]

"Splodrod" <teign2nz@yahoo.co.ukk> wrote in
news:fbb7n6$k3s$1$8300dec7@news.demon.co.uk:

Hi
When doing guitar effects mods some of them change a silicon trany for a
germanium one. Why, what effect might this have on the sound?
Cheers BB

I'll leave the finer points to people who know more, much more, but
basically germanium has a softer onset of nonlinearity, so has a smoother
kind of fuzzy aspect to the sound. Silicon will be cleaner till it
distorts, then it will distort more sharply.
I think some people like germanium for being a little more like the effects
of vaccuum tubes.

Also, if people are changing from germanium to silicon, they might not be
after a change in sound, they might just be ignoring the differences and
substituting newer transistors in older designs.

 

[Michael Black]

Lostgallifreyan (no-one@nowhere.net) writes:

Also, if people are changing from germanium to silicon, they might not be
after a change in sound, they might just be ignoring the differences and
substituting newer transistors in older designs.

He did say the reverse, putting germanium where silicon originally lie.
I wasn't sure if that was a typo.

If it is, the obvious point is that germanium transistors have basically
been superseded by silicon, and virtually nothing has been manufactured
with germanium transistors in decades. Finding germanium transistors
at this point is likely about finding old stock.

If you can't easily find or buy germanium, then obviously replacing
bad transistors doesn't leave much choice but to use silicon.

Michael

 

[Lostgallifreyan]

et472@FreeNet.Carleton.CA (Michael Black) wrote in
news:fbbnoo$h0u$1@theodyn.ncf.ca:

He did say the reverse, putting germanium where silicon originally lie.
I wasn't sure if that was a typo.

Fair, it might be that way round, I just read it one way as it's ambiguos
and I didn't notice.

It might then be that germanium transistors are sought for their sound
quality to put in new circuits. One way to do that might be to use op-amps
with germanium diodes in the feedback loop or other part of the circuit. I
have no idea how viable that is, but germanium diodes are still sold, if
not actually still made.

 

[Splodrod]

Many thanks for that.
I think the "onset of nonlinearity" is the answer.
Yes it was to replace the silicon with germanium.
Thought I read somewhere whilst trying to find an answer that some
germaniums are still made. The common ones but didn't look at the web site
date.
Cheers me dears
BB

et472@FreeNet.Carleton.CA (Michael Black) wrote in
news:fbbnoo$h0u$1@theodyn.ncf.ca:

He did say the reverse, putting germanium where silicon originally lie.
I wasn't sure if that was a typo.


Fair, it might be that way round, I just read it one way as it's ambiguos
and I didn't notice.

It might then be that germanium transistors are sought for their sound
quality to put in new circuits. One way to do that might be to use op-amps
with germanium diodes in the feedback loop or other part of the circuit. I
have no idea how viable that is, but germanium diodes are still sold, if
not actually still made.

 

[philo]

"Splodrod" <teign2nz@yahoo.co.ukk> wrote in message
news:fbb7n6$k3s$1$8300dec7@news.demon.co.uk...

Hi
When doing guitar effects mods some of them change a silicon trany for a
germanium one. Why, what effect might this have on the sound?
Cheers BB

You need to be careful as just voltage drop across a Si junction is about
0.6v (textbooks usually say 0.7)
while the Ge voltage drop is about 0.3 volts.

So if not properly compensated... you could end up with distortion
or even destroying the device

 

[Eeyore]

Splodrod wrote:

Hi
When doing guitar effects mods some of them change a silicon trany for a
germanium one. Why, what effect might this have on the sound?

Probably very little, although I wonder if they might have a slightly different
output characteristic that clips more softly.

Germanium transistors are also likely to have lower current gain than modern
silicon types and that might affect how they perform is some circuits.

Graham

 

[Eeyore]

philo wrote:

"Splodrod" <teign2nz@yahoo.co.ukk> wrote in message

When doing guitar effects mods some of them change a silicon trany for a
germanium one. Why, what effect might this have on the sound?


You need to be careful as just voltage drop across a Si junction is about
0.6v (textbooks usually say 0.7)
while the Ge voltage drop is about 0.3 volts.

Yes, the circuit will need to be adjusted to supply the different bias voltage.
Just replacing a silicon part with germanium is not likely to work very well.

Also, the germanium part is likely to have lower current gain and that may also
require circuit redesign.

Graham

 

[JeffM]

Splodrod wrote:

it was to replace the silicon with germanium.
Thought I read somewhere whilst trying to find an answer
that some germaniums are still made.

Please don't top-post in these groups.
If it's not important enough to appear above your text, trim it out.

Those parts are collector's items.
http://groups.google.com/group/sci.electronics.components/browse_frm/thread/e320b9682d365ab1/eb88f1b065c1e987?q=only.makes.optoelectronics+Oliver.Germanium
http://groups.google.com/group/sci.electronics.design/browse_frm/thread/11c31d2d8111a736/c132d5d474b0f5df?q=the-ad-campaign+Oliver.Germanium+Nowadays+zzz+Too.young.to.remember+that.Oliver.dude

 

[Ray King]

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:46D9E659.DE9FC26F@hotmail.com...

Splodrod wrote:

Hi
When doing guitar effects mods some of them change a silicon trany for a
germanium one. Why, what effect might this have on the sound?

Probably very little, although I wonder if they might have a slightly
different
output characteristic that clips more softly.

Germanium transistors are also likely to have lower current gain than
modern
silicon types and that might affect how they perform is some circuits.

Graham

I guess if one can believe that gold plated wires can change the
characteristics of an electrical carrying conductor enough that it can be
detected at an audio frequency, then, I guess that person can tell the
difference between silicon and germanium. For my self I have changed many
circuits with germanium transistors to silicon just to gain the reliability
and temperature stability of silicon. I would have never guessed that any
waveforms would have changed if they had I would have been very surprised.
Germanium transistors have many of the characteristics as silicon of the
same size except they are very leaky and continue to increase in leakage
with time and temperature. Both silicon and germanium have about a -2mv/c
Vbe temperature coefficient it just starts at 0.6v for silicon and 0.15v for
germanium.
Ray

 

[Eeyore]

Ray King wrote:

I guess if one can believe that gold plated wires can change the
characteristics of an electrical carrying conductor enough that it can be
detected at an audio frequency,

You would have to have some kind of audio-religious belief to do that since it
has no basis whatever in science/physics/materials properties. I would totally
disregard anyone who made any such specious claim.

then, I guess that person can tell the difference between silicon and
germanium

That would be quite different. For a host of possible related reasons.

Graham

 

[Lostgallifreyan]

"Ray King" <rayjking@bellsouth.net> wrote in
news:gIMCi.78682$jH3.16902@bignews6.bellsouth.net:

I guess if one can believe that gold plated wires can change the
characteristics of an electrical carrying conductor enough that it can
be detected at an audio frequency, then, I guess that person can tell
the difference between silicon and germanium. For my self I have
changed many circuits with germanium transistors to silicon just to
gain the reliability and temperature stability of silicon. I would
have never guessed that any waveforms would have changed if they had I
would have been very surprised. Germanium transistors have many of the
characteristics as silicon of the same size except they are very leaky
and continue to increase in leakage with time and temperature. Both
silicon and germanium have about a -2mv/c Vbe temperature coefficient
it just starts at 0.6v for silicon and 0.15v for germanium.

All that's assuming that people want the linear operationg region. You're
ignoring that the OP was interested in guitar effects. Germanium junctions
have a less sharp diode step change so when that's used to deliberately
clip the signal there is a big difference in the sound. It may be that the
extra leakage raises and changes the noise floor to contribute to the fuzzy
character that people are after when they specify germanium transistors.
Usually I think it was just that the onset of clipping was considered less
offensive than with silicon, and for some musicians it's important to stay
with an original technology rather than try to emulate it.

 

[Eeyore]

Ray King wrote:

For my self I have changed many circuits with germanium transistors to silicon
just to gain the reliability
and temperature stability of silicon. I would have never guessed that any
waveforms would have changed if they had I would have been very surprised.

Did you bother measuring ?

Opinion is cheap. And guesses are inded only guesses. Provide hard evidence and
I'd believe you.

Graham

 

[Lostgallifreyan]

Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote in
news:46DBB979.C928AEC3@hotmail.com:

For my self I have changed many circuits with germanium transistors
to silicon just to gain the reliability
and temperature stability of silicon. I would have never guessed that
any waveforms would have changed if they had I would have been very
surprised.

Did you bother measuring ?

Opinion is cheap. And guesses are inded only guesses. Provide hard
evidence and I'd believe you.

To add to this, some very distinct changes in sound may not be noticeable
when looking at a wave, especially those that subtly change the timing of a
long rising or falling slope. Failing to see changes in a waveform is a
very poor basis for judging the sound. That's why FFT and DCT were
invented.

 

[Jamie]

Ray King wrote:

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:46D9E659.DE9FC26F@hotmail.com...


Splodrod wrote:


Hi
When doing guitar effects mods some of them change a silicon trany for a
germanium one. Why, what effect might this have on the sound?

Probably very little, although I wonder if they might have a slightly
different
output characteristic that clips more softly.

Germanium transistors are also likely to have lower current gain than
modern
silicon types and that might affect how they perform is some circuits.

Graham


I guess if one can believe that gold plated wires can change the
characteristics of an electrical carrying conductor enough that it can be
detected at an audio frequency, then, I guess that person can tell the
difference between silicon and germanium. For my self I have changed many
circuits with germanium transistors to silicon just to gain the reliability
and temperature stability of silicon. I would have never guessed that any
waveforms would have changed if they had I would have been very surprised.
Germanium transistors have many of the characteristics as silicon of the
same size except they are very leaky and continue to increase in leakage
with time and temperature. Both silicon and germanium have about a -2mv/c
Vbe temperature coefficient it just starts at 0.6v for silicon and 0.15v for
germanium.
Ray


Talking about G-Trannies, I happen to have some new in the package of

a series of HEP if any one is interested.

If memory serves, the Hfe Gain curve is also different than the silicone.


--
"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

 

[Pieter]

On Sat, 1 Sep 2007 09:26:04 +0100, "Splodrod" <teign2nz@yahoo.co.ukk>
wrote:

Hi
When doing guitar effects mods some of them change a silicon trany for a
germanium one. Why, what effect might this have on the sound?
Cheers BB

Hi,

This is done in fuzz pedals, that generate distortion. When replacing
them, you need to adjust several resistor values too!

A silicon transistor is generally a "better" transistor, but it is the
"bad" part of the germanium transistor that is being used. It
saturates more, the gain depends on the currents more. And it is
slower.

The transistors are driven into saturation. The silicon transistor
goes up to the power supply, then clips and give sharp edges. this
gives a very sharp, mean sound.

But the germanium transistor saturates and can't even reach the power
supply voltage, it shows characteristics that look more like a
distorting tube, rounding off the peaks. But there is more to it: a
germanium transitor is much slower, has higher capacitances (i think
that that may also have to do with the older manufacturing processes).
This causes the edges of the clipping to get really round. And at the
same time, very high harmonics are not generated anymore.

So what does it do:
It generates distortion, but only a couple of harmonics (more even
than uneven harmonics), making the sound more pleasant. It gives more
"warmth". And still "power" as it works in the mid-frequency region.
It gives a sense of a "full" sound.

And now I have a great tip for you, and all you germanium distortion
enthousiasts out there: you can add a very small capacitor to the
base-collector of the distorting transistor to influence the warmth of
the sound! Notice that the capacitance must only be a couple of pf as
it is being multiplied by the transistor due to the Miller effect.

You can use this capacitor too to use another germanium transistor
(one that is cheaper than the ones that are always used) and adjust
the sound so they sound the same.

You can also influence the sound by adjusting the bias, so the
transistor will either generate even or more uneven harmonics
depending on wether distortion is on both up and down voltage, or only
one.

If you have any questions about how to calculate resistor values, feel
free to ask me. Email me at (and remove both the "byespam"'s) to
pieterbyespam@byespamhoeben.com

Pieter

 

[LVMarc]

Pieter wrote:

On Sat, 1 Sep 2007 09:26:04 +0100, "Splodrod" <teign2nz@yahoo.co.ukk
wrote:

Hi
When doing guitar effects mods some of them change a silicon trany for a
germanium one. Why, what effect might this have on the sound?
Cheers BB


Hi,

This is done in fuzz pedals, that generate distortion. When replacing
them, you need to adjust several resistor values too!

A silicon transistor is generally a "better" transistor, but it is the
"bad" part of the germanium transistor that is being used. It
saturates more, the gain depends on the currents more. And it is
slower.

The transistors are driven into saturation. The silicon transistor
goes up to the power supply, then clips and give sharp edges. this
gives a very sharp, mean sound.

But the germanium transistor saturates and can't even reach the power
supply voltage, it shows characteristics that look more like a
distorting tube, rounding off the peaks. But there is more to it: a
germanium transitor is much slower, has higher capacitances (i think
that that may also have to do with the older manufacturing processes).
This causes the edges of the clipping to get really round. And at the
same time, very high harmonics are not generated anymore.

So what does it do:
It generates distortion, but only a couple of harmonics (more even
than uneven harmonics), making the sound more pleasant. It gives more
"warmth". And still "power" as it works in the mid-frequency region.
It gives a sense of a "full" sound.

And now I have a great tip for you, and all you germanium distortion
enthousiasts out there: you can add a very small capacitor to the
base-collector of the distorting transistor to influence the warmth of
the sound! Notice that the capacitance must only be a couple of pf as
it is being multiplied by the transistor due to the Miller effect.

You can use this capacitor too to use another germanium transistor
(one that is cheaper than the ones that are always used) and adjust
the sound so they sound the same.

You can also influence the sound by adjusting the bias, so the
transistor will either generate even or more uneven harmonics
depending on wether distortion is on both up and down voltage, or only
one.

If you have any questions about how to calculate resistor values, feel
free to ask me. Email me at (and remove both the "byespam"'s) to
pieterbyespam@byespamhoeben.com

Pieter

Pieter,

You have written a very insightful piece on the basis of the "tube
sound" distortion versus solid state and also versus silicon and
germanium to regain that tube sound.

The signal characteristics you describe and categorize as a "Good warm"
versus "metallic and tinnie". The relationship to favor even and limit
odd, while limiting total harmonic offers insight into what process you
would need to create a tube sound with semi-conductors.

Best regards,

Marc